Egg allergies are the one of the most common food allergies in children, second only to milk. Fortunately, 70% of children will outgrow the allergy by age 16. Great odds, right? I’m a little more pessimistic about that given my two close relatives who never outgrew their egg allergy. But we have reason to be optimistic for Bubba. First, a little background (from this non-scientist with no medical training) on egg allergies.
As everyone knows, eggs contain whites and yolks. You can be allergic to both or only one. Allergies to egg whites (also called albumen) are far more common however. For purposes of this discussion, egg whites contain five major allergenic proteins and among those, ovomucoid is the most common target of immune system attack. “The allergenicity of proteins depends mostly, but not exclusively, on their resistance to heat and digestive enzymes.” Ovomucoid (Gal d 1) is a heat stable protein, meaning it retains its allergy-inducing properties even when cooked. Another main egg white protein, ovalbumin (Gal d 2), is far less heat stable. When heated to high temperatures, ovalbumin is broken down and not able to bind to IgE.
So how does this apply to your child? She may be allergy tested for ‘egg’, or more commonly she will be tested for ovomucoid and ‘egg white’. Here, egg white refers to ovalbumin. Based on the test results, your child may be a candidate to try a baked egg food challenge. This 2012 study at Mt. Sinai had specific recommendations about who would be an ideal challenge candidate. This 2013 study concluded that egg white IgE was superior in predicting the outcome of a baked egg challenge. Something to discuss with your allergist, obviously. Studies have demonstrated that many egg-allergic children (as many as 80%) can tolerate baked egg. This is exciting because ingestion of baked egg has been shown to actually speed resolution of an egg allergy.
Optimism for Bubba
As an infant, Bubba tested low-positive for ovomucoid and positive for egg white. We were told she would be a good candidate for trying baked egg when she got older and could tell us if she was symptomatic. In April 2014 Bubba’s ovomucoid IgE was only .49 and her egg white IgE was 1.90 (Class II). We decided to go ahead with a baked egg challenge in May 2014 which she passed. We used a recipe for cupcakes provided by our allergist. It required a specific flour-to-egg ration and had to be cooked at 350 degrees for at least 30 minutes. We conducted the challenge in our allergist’s office and had no issues. We were told to feed Bubba one of these cupcakes every day as a therapy of sorts to (hopefully) speed the resolution of her entire egg allergy. While this went well for a few days, we took a break during which she was exposed to milk (another allergen) and when we tried to resume with the cupcakes Bubba complained of a ‘spicy mouth’ and told us they ‘weren’t good for [her]’. We waited a month and tried again. Same reaction. Our allergist was at a loss but suggested some day we try again, perhaps with a smaller dose. About six months later Bubba ate a cupcake believed to be safe but accidentally made with eggs. We only found out later and were shocked that she’d had no symptoms.
We have been mentally gearing up for another attempt and fresh off our food challenge victory with Big Girl, we decided yesterday was the day. Same recipe, though this time we only fed her half a cupcake. Bubba did not know the cupcake had eggs in it. She loved it! And then got up from the table and started wiping her tongue on a dish towel. “What’s wrong Bubba?” “My mouth is itchy.” Hmmmmm. “Mom, sometimes cupcakes make my mouth itchy.” Memory like an elephant this one. “Ok. Let’s have a glass of water.” One glass of water later and she said it was gone. No other symptoms. So what would you do? Press on? We decided to try again today. Half a cupcake. She said she’d like hers with a glass of water for the itchy mouth. Ok. After she ate it she said there were no itchies because she drank water. Sounded good, but then twenty minutes later she complained of a belly ache. This went away within a few minutes (using an iPad and a wet towel on her head as distractions). Should we press on? I think we will. I plan to consult with our allergists to confirm. But I think these small, fleeting symptoms shouldn’t stop her from a potentially advantageous therapy. Even if it does give me angina.
Please share any similar experiences!
A couple additional egg allergy bits of information from my research:
- Natural resolution of an egg allergy takes longer than previously thought. ” 4% [outgrow it] by age 4 years, 12% by age 6 years, 37% by age 10 years and 68% by age 16 years.
- The longer an egg allergy persists, the less likely tolerance will develop.
- Interestingly, some children who test as allergic to eggs may get contact hives from touching eggs and yet have no reaction upon ingestion. Bubba has gotten hives from contact with eggs.
- Successful baked egg therapy creates “immunologic changes [that] parallel those seen in the natural resolution of egg allergy and associated with food oral immunotherapy (OIT).” Wow, right?
- Tolerance of baked egg does not imply that reactions to regular egg will be any less severe. Conversely, a history of severe reactions to regular egg does not predict the likelihood of passing a baked egg challenge.
- Persistent egg allergy, as opposed to a transient allergy that is outgrown, is associated with higher ovomucoid IgE levels.
- Egg allergy and eczema are closely associated. As many as 70% of children with atopic dermatitis have an egg allergy. Where both conditions are present, resolution of the atopic dermatitis generally occurs at a later age.